<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    // 异步编程
    setTimeout(()=>{
        console.log(111)
        setTimeout(()=>{
            console.log(222)
            setTimeout(()=>{
                console.log(333)
            },3000)
        },2000)
    },1000)
</script>
</body>
</html>
